The most likely author of Isaiah 12:4 is the prophet Isaiah himself. According to evangelical Christian belief, Isaiah was a prophet who lived in ancient Israel during the 8th century BC. He was called by God to deliver messages of judgment, comfort, and redemption to the people of Israel.

Isaiah is often regarded as one of the greatest prophets of the Old Testament, and his writings are considered divinely inspired by evangelical Christians. In Isaiah 12:4, the prophet speaks of giving thanks to the Lord and proclaiming his name among the nations.

Evangelical Christians believe that Isaiah’s prophecies were fulfilled in the life, death, and resurrection of Jesus Christ, and that his messages continue to be relevant for believers today. They see Isaiah 12:4 as a call to praise and worship God, and to share his message of salvation with others.